A golf club is generally provided with a club head, a shaft and a grip. Grips made from silicone resin, for example, have conventionally been provided. Forming the grip from such a material offers a better feel (comfort) of grip when the golfer grasps the club, and provides a better slip prevention effect and better wear resistance of the grips (Patent Document 1).
The impact angle between the clubface and the ball when the golfer hits the ball largely affects the ball travel direction. It is essential for the clubface to meet the ball at right angles in order for the ball to travel in a direction as intended by the golfer. The golf club receives a large impact force at the hitting moment. It is a conventional understanding that this impact force gives the following effect on the golf club: Specifically, the impact force causes torsional deformation in the shaft. This makes the clubface meet the ball at an angle inclined from the vertical, as a result of which the ball travels in a direction slightly different from the direction intended by the golfer. Various measures have been proposed in the past to reduce torsional deformation in the shaft based on this understanding (see, for example, Patent Documents 2 to 4).
It was conventionally assumed that an angle difference between intended and actual ball travel directions was primarily caused by a twist in the shaft. However, even though the shaft is improved to have higher torsional rigidity, the phenomenon in which the ball travels in a direction not exactly as aimed by the golfer still happens. The present inventor, in investigating the cause of this phenomenon, focused on the fact that the grip, which is a component of a golf club, is significantly more resilient than the shaft. The present inventor then found out that, while the impact force would obviously cause torsional deformation in the shaft, the difference between intended and actual impact angle between the clubface and the ball was actually largely dependent on resilient deformation of the grip caused by this impact force.
The present inventor assumed that an improvement in the conventional grip structure would effectively prevent a difference between intended and actual impact angle between the clubface and the ball. On the other hand, the grip is desired to be made of a soft resin for a better feel of grip as mentioned above. It is obvious that the grip will have lower torsional rigidity if it is made from such a soft material. Thus the present inventor developed, and obtained a patent (see Patent Document 5) of, a golf club grip that offers a good feel of grip and a slip prevention effect, and allows the golfer to hit the ball in a direction as intended.